1. Field of the Invention
This invention pertains to the general field of interferometric profilometry. In particular, it provides a technique for improving the resolution of an interferometric profilometer by reducing the field of view of its objective and combining multiple overlapping images to form a composite profile.
2. Description of the Prior Art
The optical resolution of the objective of an interferometer is an important parameter in the overall performance of the instrument. The spatial resolution can be enhanced by reducing the field of view of the objective, but that also reduces the capability of the instrument with respect to the area of sample being tested. If, on the other hand, the field of view is enlarged to cover a larger test surface, the optical (and therefore also spatial) resolution of the resulting image is adversely affected. Therefore, a practical balance is normally struck between the optical resolution of the profilometer and the size of the test surface that it can handle.
As interferometric technology progresses, it has become very desirable to provide some flexibility with regard to the surface size of the samples suitable for testing. This invention provides a procedure for enhancing the resolution or, alternatively, for increasing the x-y profiling range of a conventional interferometer.